Hmmm... Tour 280 with Venice... I wonder if this could be related to a typo in the battle_models.modeldb ... Belovèse found this error regarding a "heavy_infantry" unit from venice. Here is the error:
We should see if replacing advmace with mace can solve the problem...model DB 22078: (Entry venetian_heavy_infantry_ug2) Assigned non-exist primary skeleton mtw2_advmace